Experimental effects of structural enrichment on avian nest survival in a
managed forest landscape
Matt Hane1, AJ Kroll1, Josh Johnson1, Mike Rochelle1 and Ed Arnett2
1Weyerhaeuser Timberlands Research2Theodore Roosevelt Conservation Partnership
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CREATION OF SNAG HABITAT FROM EXISTING
LIVE TREES CAN BE DONE
• Background
• Study Design
• Results
• Final Thoughts
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BACKGROUND
• Transition from old forests to intensively-managed stands
• Deficiencies in snag numbers and types
• How will adequate types and numbers of snags be maintained in upland areas?
We emphasize that the complete ecological role of snags in the forest is still unknown; therefore, management strategies involving the snag resource must be flexible. --Cline et al. (1980: 785)
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BACKGROUND
• Snags were created from 1997-1999
• Inexpensive
• Safe
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BACKGROUND
• Harvest unitso Naturally regenerated 2nd growth Douglas fir standso All units were harvested with ground-based
systemso Harvester cut off tree at the highest point it could
reach• Treatments
o Density: 0.5, 1.2, and 2.5 snags/hao Clustered (5-6 trees) vs. uniformly distributed
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BACKGROUND
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STUDY DESIGN
• 2008 through 2010
• Determine rate of avian nest survival in snags created from merchantable 2nd growth
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STUDY DESIGN
• Two stage modeling process
o1st temporal variation
date, date^2, stage, date*stage, constant, global
o2ndexperimental design
year, treatment, density, dispersion, density*dispersion,
• Logistic exposure method
Shaffer, Terry L. (2004) A unified approach to analyzing nest success. Auk, 121, 526-540.
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RESULTS – Expected
"Industrial tree farms are sterile and lifeless, this particular method is incredibly ecologically
destructive."
Juliette Beck, coordinator of the Sierra Club's Stop Clearcutting Campaign,
as quoted in the San Francisco Bay Guardian Online November 9, 2011
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RESULTS – Expected
Primary cavity excavatorsChestnut-back chickadee
Downy woodpecker
Hairy woodpecker
Northern flicker
Pileated woodpecker
Red-breasted nuthatch
Red- breasted sapsucker
Walter & Maguire (2005) Snags, cavity nesting birds, and silvicultural treatments in western Oregon. Journal of Wildlife Management, 69,
1578-1591
Secondary cavity excavatorsBrown creeper
European starling
House wren
Violet-green swallow
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RESULTS yearly weather variation
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RESULTS Nest totals 2008-2010
2008 2009 2010Total
Failed Successful Failed Successful Failed Successful
CBCH 15 54 39 78 51 59 295
HOWR 9 27 10 41 4 17 108
NOFL 9 12 6 15 8 13 63
PUMA 0 6 5 4 2 3 20
HAWO 1 2 2 1 6
WEBL 2 1 1 4
RBSA 1 1 1 3
NSWO 1 1 2
RBNU 2 2
VGSW 2 2
Total 38 105 60 142 68 93 506
Yearly Success Rate 73% 70% 58% 67%
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RESULTS Chestnut-backed chickadee
• Our Studyo Apparent nest success 65%o Average daily survival 0.989
95%CL: 0.965-0.996
• Other Studieso Mahon & Martin (2006) 49%o Sperry et. al. (2008) 0.976 & 0.984
95%CL: 0.925-0.996
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RESULTS Chestnut-backed chickadee
Low density
Medium density
High density
L
M
H
L
M
H
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
2008 2009 2010
Year
Period Survival Rates
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RESULTS House wren
• Our Studyo Apparent nest success 78%o Period survival rate 0.72 95%CL: 0.52, 0.85
• Other studieso Period survival rate
• Cavities 0.63 – 0.75• Boxes 0.83
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RESULTS Northern flicker
• Our Studyo Apparent nest success 63.5%o Period survival rate 0.60 95%CL: 0.46, 0.71
• Other studieso Apparent nest success
cavities and boxes 41% -100 %o Period survival rate 0.41 – 0.80
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RESULTS Purple martin
• Our Studyo Apparent nest success 65%o Period survival rate 0.70 95%CL: 0.48, 0.84
• Other studieso Nest box success 38.5% - 84.3%
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• Leaving created snags at a density of 0.5/ha retains some cavity-nesting bird species
o Up to years 12-15…
• Benefits restricted by rotation age
o Snags must be created from trees growing in unit
o Suitability is also dependent on stand conditions (e.g., site index) and landscape context
• Different strategies are required to provide tall snags
• Other taxa besides birds?
FINAL THOUGHTS
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FINAL THOUGHTS
• Ed Arnett
• Weyerhaeusero South Valley Operations
for creating units and snags
o Supporting research
• Oregon Forest Industries Council (OFIC)
• Field crews 2008-2010
Acknowledgements
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